基质中铁碳-沸石填充方式对人工湿地温室气体排放的影响

Influence of substrate filling method and volume ratio on greenhouse gases emissions from iron carbon-zeolite constructed wetlands

人工湿地在污水治理中已获得广泛应用,但其温室气体排放通量是自然湿地的2~10倍,对人工湿地温室气体的减排已是亟待解决的问题。通过在温室构建潜流人工湿地系统装置,均为间歇曝气,设立不同填料的填充配比和填充顺序,分别为:添加20%铁碳+80%沸石(其中铁碳在上层沸石在下层记为T2F8,铁碳在下层沸石在上层记为F8T2,下同)、40%铁碳+60%沸石(记为T4F6和F6T4)、60%铁碳+40%沸石(记为T6F4和F4T6)、以添加100%沸石为对照组(F),探究了基质的填充方式对人工湿地系统中温室气体排放的影响。结果表明,与铁碳填充在表层的湿地组1(T2F8、T4F6、T6F4)相比,铁碳填充在底层的湿地组2(F8T2、F6T4、F4T6)均显著实现了人工湿地中CH4、N2O的减排(P<0.05);同时,铁碳-沸石体积比对CH4、N2O减排效果影响显著,且铁碳占比越低CH4和N2O排放越少(P<0.05);典型周期中曝气段出现CH4和N2O排放峰值,湿地F8T2的排放峰值均显著低于其他湿地(P<0.05),其综合GWP最大减排值达到75.82%。铁碳填充在底层及铁碳-沸石体积比为2:8铁碳-沸石人工湿地(F8T2)的综合GWP最低,温室气体的减排效果最好。本研究结果可为人工湿地温室气体减排的实践提供参考。

Constructed wetlands have been widely used in wastewater treatment, but the greenhouse gas flux from constructed wetlands is two to ten times higher than that from natural wetlands, so there is an urgent need to reduce greenhouse gas emissions from constructed wetlands. In this study, a submerged wetland system was constructed in a greenhouse with different filler ratios and filling sequences: 20% Fe carbon filler+80% zeolite filler+intermittent aeration(where Fe carbon in the upper zeolite layer is denoted as T2F8 and Fe carbon in the lower zeolite layer is denoted as F8T2, hereinafter), 40% Fe carbon filler+60% zeolite filler+intermittent aeration(denoted as T4F6 and F6T4), 60% FeC filler+40% zeolite filler+intermittent aeration(denoted as T6F4and F4T6), and 100% zeolite filler+intermittent aeration as the control group(F), to investigate the effect of substrate filling method on greenhouse gas emissions in the constructed wetland system. The results showed that compared with the iron carbon filled wetland group 1(T2F8, T4F6, T6F4), the iron carbon filled wetland group2(F8T2, F6T4, F4T6) significantly reduced the CH4and N2O emissions in the constructed wetland(P<0.05).The lower the proportion of iron carbon, the lower the CH4and N2O emission(P<0.05);the peak of CH4and N2O emission in the aeration section in a typical cycle, the peak of emission in wetland F8T2 is significantly lower than other wetlands(P<0.05), and the maximum reduction of its integrated GWP reaches 75.82%. In total,the FeC-filled substrate and the FeC-zeolite constructed wetland with a 2:8 FeC-zeolite volume ratio(F8T2) had the lowest integrated GWP and the best GHG reduction.